Remove unused ownership argument to GrSurfaceProxy::MakeWrappedBackend

This is the last public reference to GrWrapOwnership, so removal paves
the way for moving it to somewhere internal.

BUG=skia:

Change-Id: I876298642ff812452a644c1d2b9519691eac44b9
Reviewed-on: https://skia-review.googlesource.com/9492
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2 files changed